Noncontrolling Interests (Schedule Of Redeemable Noncontrolling Interest) (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Activity in redeemable noncontrolling interest
Beginning balance	$ 1,175,594
Net income attributable to redeemable noncontrolling interest	34,327	$ 44,591
Ending balance	1,187,991		$ 1,175,594
DaVinciRe Holdings Ltd.
Activity in redeemable noncontrolling interest
Beginning balance	994,458	930,955	930,955
Redemption of shares from redeemable noncontrolling interest	(63,642)	(90,818)
Sale of shares to redeemable noncontrolling interests	23,921	43,040
Net income attributable to redeemable noncontrolling interest	31,909	42,964
Ending balance	986,646	926,141	994,458
RenaissanceRe Medici Fund Ltd.
Activity in redeemable noncontrolling interest
Beginning balance	181,136	115,009	115,009
Redemption of shares from redeemable noncontrolling interest	(10,625)	(940)	(21,700)
Sale of shares to redeemable noncontrolling interests	28,416	39,500	79,500
Net income attributable to redeemable noncontrolling interest	2,418	1,627
Ending balance	$ 201,345	$ 155,196	$ 181,136